Working with Drives with a chekcedComboboxEdit and one TreeList(TreeNode View) of the DevExpress Components

I have one CheckedComboBoxEdit and one TreeList(TreeNode View) components (DevExpress Components). I am loading drives in the CheckedComboBoxEdit with the below code Lines:

string[] drives = Environment.GetLogicalDrives();
foreach (string drive in drives)
    {
        chkBxCboBx1MainFrm.Properties.Items.Add(drive);

    }//End Of Filling The Checked ComboBox With Drives List.

As I check a drive in the ComboBox,I want the checked Ones add to treelist(treeNodeView) and behave as a Drive, but the attached exception is pop up.

I'll be thankful if you guide me through

the error attached